The present invention relates quite generally to the operation of LEDs, with this being understood to mean inorganic LEDs and organic LEDs (OLEDs).
In principle, it is already known to supply electrical power to an LED section which can have one or more LEDs connected in series, from a constant current source. It is likewise known to use PWM modulation to implement dimming, with the result that the mentioned constant current regulation is implemented in the switch-on time periods of a PWM pulse train. During dimming, therefore, the duty factor of the PWM signal is then varied.
In order to provide the supply voltage of the constant current source, an actively clocked PFC (Power Factor Correction) circuit can be used, for example.
Finally, further demands also need to be taken into consideration during operation of LEDs, for example the fact that, generally, DC isolation between the LED section and the supply voltage of the PFC, typically an AC system voltage, is required.